more likely, you have a newer software version that the one that is distributed for installation in the prs650 firmware, so yours works, but the older one does not. but I am not fussed enough to want to reinstall & check version numbers etc. ( another possible is that the old software will work if you've previously connected OK but not if you are new user, with no account created ? )
its not my PC - i googled the exact error message about "firewalls" & lots of other people get it also- the error message detail is in- post#2 of this thread
https://www.mobileread.com/forums/sho...light=firewall
PS adobe says that I must update my passrod- won't let me log into their suite until I do, but as my PC & device authoriastions still work I shall leave it as is